화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.117, No.45, 11548-11557, 2013
Experimental Characterization of C-X center dot center dot center dot Y-C (X = Br, I; Y = F, Cl) Halogen-Halogen Bonds
Using FTIR and Raman spectroscopy, we investigated the formation of halogen bonded complexes of the trifluorohalomethanes CF3Cl, CF3Br, and CF3I with the halomethanes CH3F and CH3Cl and the haloethanes C2H5F and C2H5Cl dissolved in liquid krypton. For CF3Br and CF3I, evidence was found for the formation of C-X center dot center dot center dot F and C-X center dot center dot center dot Cl halogen bonded 1:1 complexes. Using spectra recorded at different temperatures, we determined the complexation enthalpies for the complexes to be -7.0(3) kJ mol(-1) for CF3Br center dot CH3F, -7.6(1) kJ mol(-1) for CF3I center dot CH3F, -5.9(2) kJ mol(-1) for CF3Br center dot CH3Cl, -8.3(3) kJ mol(-1) for CF3I center dot CH3Cl, -7.1(1) kJ mol(-1) for CF3Br center dot C2H5F, -8.7(2) kJ mol(-1) for CF3I center dot C2H5F, -6.5(2) kJ mol(-1) for CF3Br center dot C2H5Cl, and -8.8(3) kJ mol(-1) for CF3I center dot C2H5Cl. For all halogen bonded complexes with a fluorine-electron donor, a blue shift ranging from +0.6 to +1.5 cm(-1) was observed for the C-X stretching mode. The results from the cyrospectroscopic study are compared with ab initio calculations at the MP2/aug-cc-pVDZ(-PP) level.